Differences in hormone levels around parturition in Hanwoo cattle (Bos taurus coreanae) following artificial insemination and embryo transfer

Background With unique genetic traits, Hanwoo cattle (Bos taurus coreanae) are well‐adapted to the Korean environment. However, their perinatal mortality rate is 2%–3%, which imposes an economic burden. Objective Due to insufficient data on hormonal changes around parturition, the timing of parturition is often predicted subjectively; few studies have examined hormones in Hanwoo cattle. We measured the changes in various hormones around parturition, to seek an objective predictor of parturition time. Methods In 14 female Hanwoo cattle, we measured progesterone, prolactin and cortisol concentrations daily in jugular vein blood samples, beginning 6 days before parturition until 7 days after parturition. Conception was induced in five animals using artificial insemination. Nine animals received embryo transfer. Results During parturition, the concentration of progesterone decreased significantly in the embryo transfer group (n = 9) and in the total population (n = 14); it did not change significantly in the artificial insemination group (n = 5). Prolactin concentration increased on the day of parturition but did not differ significantly among the groups. Cortisol remained constant throughout the study course. Conclusion We concluded that parturition time can be predicted in Hanwoo cattle using progesterone concentration. This knowledge can reduce perinatal mortality, which would help to improve farm income and animal welfare.